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A008919
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n written backwards is a nontrivial multiple of n.
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5
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1089, 2178, 10989, 21978, 109989, 219978, 1099989, 2199978, 10891089, 10999989, 21782178, 21999978, 108901089, 109999989, 217802178, 219999978, 1089001089, 1098910989, 1099999989, 2178002178, 2197821978, 2199999978, 10890001089
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| D. Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986.
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LINKS
| Eric Weisstein's World of Mathematics, Reversal
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FORMULA
| Theorem (David W. Wilson): If reverse(n) = k*n in base 10, then k = 1, 4 or 9. Hence A008919 is union of A001232 and A008918.
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PROG
| (Haskell)
a008919 n = a008919_list !! (n-1)
a008919_list = [x | x <- [1..],
let (x', m) = divMod (a004086 x) x, m == 0, x' > 1]
-- Reinhard Zumkeller, Feb 03 2012
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CROSSREFS
| Cf. A001232, A008918. Reversals are in A031877.
Cf. A004086.
Sequence in context: A175698 A110819 A071685 * A110843 A023093 A001232
Adjacent sequences: A008916 A008917 A008918 * A008920 A008921 A008922
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KEYWORD
| nonn,base,nice,changed
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Corrected and extended by David W. Wilson (davidwwilson(AT)comcast.net) Aug 15 1996, Dec 15 1997.
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